最新刊期
卷 39 ， 期 1 ， 2024
-
Response properties and biomimetic design of graphene oxide/liquid crystal network composite films AI导读
摘要：Liquid crystal network （LCNs） is a liquid crystal polymer moderately crosslinked， and has the elasticity of polymer and the anisotropy of liquid crystal， including multi-stimulus response， reversible drive and programmable shape deformation properties. Therefore， it has good field responsiveness， molecular synergy and elasticity. Graphene oxide film has excellent photothermal conversion performance， and light has excellent properties such as environmental protection and remote controllability， so photodeformable graphene oxide/liquid crystal networks（GO-LCNs） have gradually become the focus of research. It can produce flexible robots， bionic photothermal actuators and other advanced devices， and has a good development prospect. In this paper， we prepared graphene oxide films on two thickness of liquid crystal network to obtain the composite film， and tested the response performance under heating stage or infrared light. The results provide an experimental basis for the application design of the composite membrane， and on this basis， the bionic device of GO-LCNs composite membrane is designed.关键词：Liquid crystal network;graphene oxide;Biomimetic application- 258
- |
- 53
- |
- 0
发布时间：2024-02-21 - 摘要：By controlling the arrangement of liquid crystal molecules，liquid crystal spatial light modulators （LC-SLM） modulate light through changing external voltage intensity. Recently，the importance of LC-SLM applicable in ultra-violet region continuously increases due to multiple applications such as photo-polymerization 3D printing. However， the vast majority of liquid crystal materials are organic compounds that absorb light and react in ultraviolet band. To expand the application band of liquid crystal materials， this paper designs a class of liquid crystal materials that do not absorb or react to light in the 325~400 nm band by selecting functional groups that do not absorb or react to light in the application band and simulating the ultraviolet-visible spectrum of the liquid crystal materials to verify the rationality of the design. The ultraviolet stability of the liquid crystal materials is compared with that of two common mixed liquid crystal materials after the ultraviolet-resistant liquid crystal compound is configured into a mixed liquid crystal material. After being irradiated by a 325 nm ultraviolet light source for 120 min， the absorbance and phase transition temperature of the liquid crystal material hardly change， the birefringence changes by 0.04%， the threshold voltage changes by 1.39%， and the response time changes by 0.32%.关键词：liquid crystal material;UV stability;birefringence
- 100
- |
- 36
- |
- 0
发布时间：2024-02-21
Material Physics
- 摘要：A frequency reconfigurable antenna with a liquid crystal polymer as the dielectric substrate is designed to realize the impedance matching of the antenna by adjusting the position and size of the patch. A polymer-dispersed liquid crystal film is prepared as the medium of the antenna， and its effect is examined on the basis of various liquid crystal to polymer ratios and film thicknesses. Under the action of an electric field， the formed liquid crystal microdroplets are reoriented and arranged along the direction of the electric field. The frequency reconfigurable antenna is then realized by changing the magnitude of driving voltage. After comparative analysis， it is concluded that the polymer-dispersed liquid crystal film with a liquid crystal content 70% （mass fraction） has the best effect， achieving continuous frequency adjustment of 62 MHz under a driving voltage of 48 V， and the maximum gain of the antenna is 3.5 dBi.This frequency reconfigurable patch antenna based on liquid crystal polymer is simple in structure， small in size， light in weight， and is easy to be integrated into a variety of mobile devices， which has a promising future for development.关键词：Liquid crystal polymer;frequency adjustable;Patch antenna
- 102
- |
- 51
- |
- 0
发布时间：2024-02-21 - 摘要：Reflective liquid crystal display （LCD） has the advantages of low power consumption and green environmental protection. However， due to the lack of optical films such as brightness enhancement film to modulate the viewing angle， the viewing angle curve under the common dot morphology has problems such as jump and unevenness. In order to improve the viewing angle of reflective liquid crystal display， a simulation model of reflective liquid crystal module is established to explore. Firstly， the viewing angle problems of the front light module are analyzed. Then， the influence of the dot morphology of the dots on the viewing angle is analyzed by taking the conical and truncated cone dots as examples. The prismatic dots are proposed to improve the viewing angle. The simulation results show that the prismatic dots can effectively solve the problem of ±35° angle curve jumping and unevenness perpendicular to the direction of incident light， and the brightness of the center of the viewing angle is increased by 52.3% compared with the conical dot. This study has important reference significance for the perspective design of reflective liquid crystal display devices.关键词：Front light module;Dot morphology;light guide plate;viewing angle
- 72
- |
- 45
- |
- 0
发布时间：2024-02-21 - 摘要：In order to solve the problem that the color of the reflective display color electrowetting display is inconsistent under ambient light with different color temperatures， which affects the color reproduction of the displayed picture， a color correction method based on the spectral reflectance characteristics of color electrowetting display is proposed. The spectral correspondence of the display color under ambient light with different color temperatures is obtained through the spectral reflectance characteristics of color electrowetting display， so as to establish the mapping relationship of the display color of color electrowetting display under ambient light with different color temperatures. According to the mapping relationship， the input color data is corrected to reduce the color difference of the displayed colors under ambient light with different color temperatures. The experimental results show that the chromaticity data of 100 test color blocks before and after the correction by the method in the two experimental light sources are reduced by 55% and 35% respectively with the average color difference of the standard light source， and the average subjective evaluation Z-scores of the corrected display images are 0.45 and 0.25.关键词：electrowetting display;ambient light;color difference;spectral properties;color correction
- 44
- |
- 42
- |
- 0
发布时间：2024-02-21 - 摘要：In order to improve the performance of thin film transistors （TFT）， the high-performance ZTO thin film transistors is prepared on SiO2/p-Si substrates based on radio frequency magnetron sputtering technology， using zinc tin oxide （ZTO） material as the channel layer. The effects of sputtering power on the surface morphology and optical properties of ZTO thin films were studied using AFM， XRD，and UV-Vis.The electrical performance of ZTO thin film transistors is tested using a Semiconductor Device Analyser. XPS analysis is used to study the influence of sputtering power on the elemental composition and valence states in ZTO thin films， and to explore the principle and mechanism of high-performance thin film transistors. The results show that all ZTO thin film samples have an amorphous structure， dense surface， and transmittance greater than 90%. The electrical performance of ZTO thin film transistors can be improved by increasing the sputtering power appropriately. The thin film transistor prepared at 90 W sputtering power has the good comprehensive performance， with saturation mobility of 15.61 cm2/（V·s）， subthreshold swing of 0.30 V/decade， threshold voltage of -5.06 V， and current switching ratio of 8.92×109.关键词：thin-film transistor;sputtering power;XPS analysis;ZTO thin film
- 110
- |
- 42
- |
- 0
发布时间：2024-02-21
Device Physics and Device Preparation
- 摘要：The task of camouflaged object segmentation is to accurately classify and localize objects that are highly similar to the background using pixel-level segmentation masks， which is more challenging than traditional object segmentation tasks. Aiming at the problems that the target is highly similar to the surrounding environment， the boundary is blurred， and the contrast is low， a camouflaged target segmentation method based on edge enhancement and feature fusion is constructed. First， a set of edge extraction modules is designed， aiming to accurately segment valid edge priors. Afterwards， a multi-scale feature enhancement module and a cross-level feature aggregation module are introduced to mine multi-scale contextual information within and between layers， respectively. In addition， a simple inter-layer attention module is proposed to effectively filter out the interference information existing after fusion by utilizing the difference between adjacent layers. Finally， accurate prediction results are obtained by combining feature maps of all levels with edge priors step by step. Experimental results show that the model outperforms other algorithms on four camouflaged target benchmark datasets. Among them， the weighted F value increased by 2.4%， the average absolute error decreased by 7.2%， and the segmentation speed reached 44.2 FPS under the RTX 2080Ti hardware environment. Compared with existing methods， this algorithm can segment camouflage targets more accurately.关键词：deep learning;Camouflaged object;image segmentation;Edge feature;feature fusion
- 263
- |
- 42
- |
- 0
发布时间：2024-02-21 - 摘要：In order to solve the problems of low segmentation accuracy and fuzzy boundary information of weld defects in X-ray films， this paper proposes an improved Dilated_Pooling_Unet （DP_Unet） network segmentation model. First of all， the codec information extraction module DP_block is added between up and down sampling， aiming to preserve the original defect semantic information to the greatest extent and reduce the loss caused by continuous convolution and pooling operations after down sampling. In addition， the GAM attention mechanism is added to the model to focus on welding. The seam defect part can effectively improve the learning ability of defect feature channels and reduce the influence of background noise. Finally， a hybrid loss function combining binary cross entropy and DiceLoss is proposed to solve the problems of unbalanced positive and negative data during network training. The experimental dataset is composed of the public dataset GDX-ray defect dataset. Experiments show that the method proposed in this paper has a good performance on the GDX-ray dataset， the Dice value reaches 93.45%， which are significantly improved compared with the baseline algorithm. This method has good segmentation performance， is superior to traditional segmentation algorithms， and effectively improves the segmentation accuracy of negative weld defects.关键词：welding detection;defect segmentation;DP_Unet;attention mechanism
- 345
- |
- 48
- |
- 0
发布时间：2024-02-21 - 摘要：In order to solve the problems of large amount of computation and difficulty in removing background noise when the local contrast method is used in star map spatial target detection， a method based on fast local contrast and target features is proposed to detect the target. Through three steps of before， during and after contrast calculation， the real-time performance of the algorithm is improved， the complex background is suppressed and the noise is removed. Firstly， high frequency noise is removed by median filtering. Then， the target region is determined by fast local maximum filtering， and the background is suppressed by local contrast calculation to highlight the imaging features of the target. Finally， according to the imaging features of the target， three feature functions are set， namely target energy distribution， target energy concentration and target energy transfer. By setting the feature threshold， noise is removed and the real target is extracted.The experimental results show that the proposed method has advantages in detection rate and time consumption. For the target with a signal-to-clutter ratio of 1.5， the detection rate is 95%， and the average time is only about 1/30~1/6 of some comparison methods.The method proposed in this paper is more suitable for rapid target detection under complex star map background conditions， and meets the requirements of strong robustness and high real-time performance of the spatial target detection algorithm of star map.关键词：Star map space object;object detection;human visual system;local contrast;Fast maximum filtering;Target feature
- 239
- |
- 38
- |
- 0
发布时间：2024-02-21 -
Pointpillars point cloud detection network based on knowledge distillation and location guidance AI导读
摘要：Lidar data is widely used in 3D target detection tasks due to its geometric characteristics. Due to the sparsity and irregularity of point cloud data， it is difficult to achieve the balance between the quality of feature extraction and the speed of reasoning. In this paper， a three-dimensional target detection algorithm based on body-column feature coding is proposed. Based on Pointpillars network， the Teacher-Student model framework is designed to distill the regression frame scale， increase distillation loss， optimize the training network model， and improve the quality of feature extraction. In order to further improve the model detection effect， the positioning guidance classification item is designed to increase the correlation between classification prediction and regression prediction， and improve the object recognition accuracy. The improvement of this network does not introduce additional network embedding. The experimental results of the algorithm on the KITTI dataset show that the average accuracy of the reference network in 3D mode is improved from 60.65% to 64.69%， and the average accuracy of the aerial view mode is improved from 67.74% to 70.24%. The model reasoning speed is 45 FPS， which meets the real-time requirements while improving the detection accuracy.关键词：Laser Point Cloud;3D object detection;knowledge distillation;Classification Confidence- 279
- |
- 41
- |
- 0
发布时间：2024-02-21 - 摘要：A point cloud alignment algorithm based on statistical local feature description and matching is proposed to address the problems of poor robustness and low alignment accuracy of the ICP algorithm in the presence of poor initial positional， partial data loss， and noise interference. Firstly， a 4-dimensional statistical local feature descriptor is constructed using point cloud local density， point cloud fitting plane distance variance， Gaussian curvature， and mean curvature to accurately describe the local features of the query points. Then， the corresponding points are matched by the feature difference between point pairs to eliminate the wrong point pairs and solve the problems of missing data and noise interference in part of the point cloud. Finally， the mean matching distance （MMD） is used as a metric to improve the alignment accuracy. MMD is a metric to improve the ICP algorithm to align the point clouds and solve the problem of low alignment accuracy when the initial poses are poor. The experimental results show that the algorithm improves the alignment accuracy by at least one order of magnitude and saves the alignment time in the case of poor initial poses， partial data loss， and noise interference， showing significant advantages in terms of robustness and alignment accuracy.关键词：point cloud registration;Feature description;feature matching;Mean match distance;ICP
- 267
- |
- 34
- |
- 0
发布时间：2024-02-21 - 摘要：To solve the problem that UAV target tracking is difficult to achieve robust tracking due to its vulnerability to perspective changes， partial occlusion， background clutter and other factors， a UAV target tracking algorithm with double response anomaly constraints is proposed. Firstly， by calculating the local response change vector and global response peak side lobe ratio， the algorithm dynamically updates the spatial regularization parameters online to reduce the influence of boundary effect. Secondly， aiming at the problem that the parameters of the time regularization term in the STRCF algorithm are fixed， the judgment mechanism of abnormal response peak is proposed， the sub-peak response coefficient is calculated， and it is fused into the time regularization parameter for real-time update， so as to avoid the tracking drift problem caused by the target template variation. The objective function is iteratively solved by alternate direction multiplier method. A large number of experiments are conducted on UAV123， UAV20L and DTB70 UAV data sets and with representative target tracking algorithms. The results show that the accuracy of UAV123 data set reaches 71.7%， and the average tracking speed of DTB70 data set reaches 48.3 frame/s. Compared with the existing UAV target tracking algorithms based on correlation filtering， the algorithm proposed in this paper has better performance， high real-time performance and robustness， and can better complete UAV target tracking.关键词：target tracking;Correlation filtering;Peak side lobe ratio;Alternating direction multiplier
- 248
- |
- 34
- |
- 0
发布时间：2024-02-21 -
Improved YOLOv5 lightweight binocular vision UAV obstacle avoidance algorithm based on Ghost module AI导读
摘要：To address the issue of autonomous obstacle avoidance during unmanned aerial vehicle （UAV） flight in outdoor environments， a lightweight binocular vision-based UAV obstacle avoidance algorithm was proposed utilizing Ghost module to improve YOLOv5. Firstly， the Ghost module was introduced to enhance the CBL and CSP_X units of YOLOv5， while utilizing- 312
- |
- 40
- |
- 0
发布时间：2024-02-21
Image Processing
- Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China 130033 Postal code：130033
- Tel：0431-86176059 Email：yjxs@ciomp.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 吉ICP备11002662号-17
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0